Effect of metal loadings on NOx and SO2 adsorption by activated carbon investigated by density functional theory

Abstract

The study of metal loadings on activated carbon for NO_x and SO₂ adsorption provides optimization strategies for developing high-performance adsorbents. This work employs density functional theory calculations to systematically investigate the adsorption energy, charge transfer, surface electrostatic potential, and interaction region variations during the single-component adsorption and co-adsorption of NO, NO₂, N₂O, and SO₂ on activated carbon loaded with 14 different metals. The results exhibit a strong regularity, showing that group IA elements (Li, Na, K) and group IB elements (Cu, Ag, Au) promote the initial surface adsorption of NO and NO₂ while inhibiting SO₂ adsorption, whereas group IIA elements (Be, Mg, Ca) and a group IIB element (Zn) enhance NO₂ adsorption but suppress N₂O adsorption. Metal atoms, acting as electron donors, can facilitate the co-adsorption of N₂O, SO₂, and NO by regulating surface electron density. Conversely, the same electron-donating effect can induce electrostatic repulsion, thereby hindering the co-adsorption of NO₂ and NO. The distinct electronic properties of each metal result in specific influences on adsorption behavior. Additionally, this study proposes a new approach for predicting superior modified metals based on strong regularity. These findings provide a more comprehensive theoretical foundation for the design of next-generation denitrification and desulfurization technologies.